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Abstract Silver nanoparticles loaded fibrillar collagen-chitosan matrix (CC) was prepared by biomimetic approach by blending silver nanoparticles (tAgNPs), collagen fibril and chitosan hydrogel followed by cross-linking and biomineralization. Electron micrograph showed that the surface of the composites exhibited native fibrillar morphology of collagen and their cross-section revealed layer-like arrangement of native fibrillar collagen. The mineralized composites exhibited surface mineralization of calcium phosphates incorporated with magnesium. FT-IR ATR analysis revealed the uniform blending of collagen and chitosan without any chemical interaction between them. XRD analysis showed incorporation of silver nanoparticles and lamellar structure of collagen and chitosan. The mechanical property of the dry composite film showed increase in tensile strength with the addition of chitosan and raised to 4.6 fold in M-CC4 composite. The incorporation of chitosan in M-CC3 led to 2.2 fold increase in mineralization as confirmed by the TGA analysis. Contact angle analysis revealed the hydrophilic nature of the composite. Hemolysis analysis of the composites verified the hemocompatible nature of composites with hemolysis < 5%. MTT assay for the composites was carried by seeding MG-63 cells and indicated cell viability > 80%. Antibacterial activity analysis showed the percent growth inhibition of about 27% and 37% for S. aureus and E. coli respectively. The prepared composite would possess silver nanoparticles loaded collagen fibril in the native state and the formed biomineral will be similar to the bone mineral. Hence the fabricated composite -could be used as a biomaterial for bone tissue engineering applications. Highlights • Nanosilver and chitosan incorporated native collagen fibril exhibit D-periodicity. • Fabrication of composites with layered collagen fibrils and calcium phosphate • Biocompatible composite with mechanical stability and antibacterial property • Novel process to incorporate silver and chitosan onto native fibrillar collagen. [ABSTRACT FROM AUTHOR]

The potential of x-ray powder diffraction to analyze the size and ultrastructure of metallic nanoparticles (silver, gold, silver-gold alloy, and calcium phosphate) is demonstrated. By the Rietveld analysis, it is possible to estimate the crystallite size for such nanoparticles, even if they are very small (4 nm), using the effect of peak broadening in small crystallites. The results correspond well to crystallite size as determined by transmission electron microscopy (TEM), also confirming the twinned nature of the metallic nanoparticles. For calcium phosphate nanorods which are not twinned, the results by x-ray powder diffraction and TEM are in good agreement. [ABSTRACT FROM AUTHOR]

Abstract: Isothermal sections of the ternary Cr–Al–Nb phase diagram were experimentally investigated for temperatures of 1150, 1300, and 1450°C by electron-probe microanalysis (EPMA), X-ray diffraction (XRD), differential thermal analysis (DTA) and light-optical (LOM) as well as scanning electron microscopy (SEM). Cr–Al–Nb alloys were prepared by levitation melting and annealed at temperatures between 1150 and 1450°C for up to 1500h. The most striking feature of the ternary Cr–Al–Nb phase diagram is the extended phase field of the cubic C15 and the hexagonal C14 Laves phase Nb(Cr,Al)2. With increasing Al content, the Laves phase polytype changes from C15 to C14. Both phase fields are separated by a small two-phase field, which shifts to lower Al contents with increasing temperature. The lattice parameters of both Laves phase polytypes and of all other phases occurring in this system were studied in dependence on composition and the solubilities of ternary elements in the binary phases were established. [Copyright &y& Elsevier]

Abstract: Partial isothermal sections of the Fe–Al–Nb phase diagram at 1000, 1170, and 1300°C as well as the corresponding part of the liquidus surface were established experimentally for Nb contents in the range from 0 to 33at%. This part of the phase diagram is characterized by an extended two-phase field of the (αFe) solid solution (disordered A2) or FeAl (ordered B2) with the Nb(Fe,Al)2 Laves phase. The solubility of Nb in all Fe–Al phases is small and reaches a maximum in the phase FeAl. A deep eutectic valley runs parallel to the Fe–Al axis across the large two-phase field and continues to the Al corner. The composition dependence of the eutectic temperature and the exact position of the eutectic valley on the liquidus surface including the Al-rich part were determined. The high-temperature phase equilibria are strongly affected by the liquid phase coming from the Al corner. With increasing temperature its phase field grows quickly into the ternary system resulting in a strongly reduced extension of the (αFe)+Nb(Fe,Al)2 two-phase field at 1300°C. [Copyright &y& Elsevier]

The aim of this study was to analyze in vitro the fatigue resistance of nickel–titanium (NiTi) and CuNiTi orthodontic wires when subjected to forces and fluids which are present intraorally. The wires were subjected to dynamic mechanical analysis (DMA) while they were immersed into different fluids with mechanical loading parameters similar to those that are subjected in the mouth. The characteristic temperatures of transitions and a rough surface structure on the perimeter of the wires were determined by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), respectively, before and after the DMA experiments. Stainless steel wires were used for comparison. In general, NiTi wires fractured earlier than the stainless steel specimens. Survival times were lower for the NiTi wires when immersed in fluids (water, citric acid, NaCl solution, artificial saliva, and fluoridated artificial saliva) than in air. SEM surface analysis showed that the NiTi and CuNiTi wires had a rougher surface than steel wires. The fracture occurred within a short number of loading cycles. Until fracture occurred, the mechanical properties remained mostly constant. [Copyright &y& Elsevier]

The Fe–Al–Nb phase diagram including isothermal sections at 1000, 1150, and 1300 °C as well as the liquidus surface and corresponding reaction scheme was studied experimentally by a combination of scanning electron microscopy (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD), and differential thermal analysis (DTA). No genuinely ternary intermetallic phase exists in the system, but the two Fe–Nb phases NbFe 2 (C14-type Laves phase) and Fe 7 Nb 6 (μ phase) have extended homogeneity ranges in the ternary system, where large amounts of Fe can be substituted by Al in both cases. The solubility of the third element was studied for all binary phases and the effect on the lattice parameters is discussed. From analysis of the as-cast microstructures and DTA experiments, the liquidus surface including all invariant reactions as well as the occurring solid state reactions were established. Three ternary eutectics, one eutectoid, and two peritectic reactions were found, and the list of invariant points is completed by seven U-type reactions. [ABSTRACT FROM AUTHOR]

The surface properties of poly-3-hydroxybutyrate (P3HB) membranes were modified using oxygen and an ammonia radio-frequency (RF, 13.56 MHz) plasma. The plasma treatment procedures used in the study only affected the surface properties, including surface topography, without inducing any significant changes in the crystalline structure of the polymer, with the exception being a power level of 250 W. The wettability of the modified P3HB surfaces was significantly increased after the plasma treatment, irrespective of the treatment procedure used. It was revealed that both surface chemistry and surface roughness changes caused by the plasma treatment affected surface wettability. A treatment-induced surface aging effect was observed and resulted in an increase in the water contact angle and a decrease in the surface free energy. However, the difference in the water contact angle between the polymers that had been treated for 4 weeks and the untreated polymer surfaces was still significant. A dependence between cell adhesion and proliferation and the polar component of the surface energy was revealed. The increase in the polar component after the ammonia plasma modification significantly increased cell adhesion and proliferation on biodegradable polymer surfaces compared to the untreated P3HB and the P3HB modified using an oxygen plasma. [ABSTRACT FROM AUTHOR]

As a measure of the prevention of implant associated infections, a number of strategies have been recently applied. Silver-containing materials possessing antibacterial activity as expected might have wide applications in orthopedics and dentistry. The present work focuses on the physico-chemical characterization of silver-containing hydroxyapatite (Ag-HA) coating obtained by radio frequency (RF) magnetron sputtering. Mechanochemically synthesized Ag-HA powder (Ca 10− x Ag x (PO 4 ) 6 (OH) 2− x , x = 1.5) was used as a precursor for sputtering target preparation. Morphology, composition, crystallinity, physico-mechanical features (Young's modulus and nanohardness) of the deposited Ag-HA coatings were investigated. The sputtering of the nanostructured multicomponent target at the applied process conditions allowed to deposit crystalline Ag-HA coating which was confirmed by XRD and FTIR data. The SEM results revealed the formation of the coating with the grain morphology and columnar cross-section structure. The EDX analysis confirmed that Ag-HA coating contained Ca, P, O and Ag with the Ca/P ratio of 1.6 ± 0.1. The evolution of the mechanical properties allowed to conclude that addition of silver to HA film caused increase of the coating nanohardness and elastic modulus compared with those of pure HA thin films deposited under the same deposition conditions. [ABSTRACT FROM AUTHOR]

The method to decrease of the porosity (densification) of crystalline spherical particles of the solid substitution solution, obtained by the method of precipitation from aqueous solution followed by low temperature crystallization of the amorphous intermediate product was proposed. The comparative analysis of morphology and structure of the particles before and after densification have been carried. It has been established that porosity of (Y1-xEux)2O3 particles has decreased 5 times compared to their initial state. It has been shown that densification process of the (Y1-xEux)2O3 spherical particles changes their morphology and structure: the size of the crystals doubles, the number and area of crystalline boundaries decrease, the intercrystalline spaces, which forming pores, are almost absent. [ABSTRACT FROM AUTHOR]

In this work, we describe fabrication techniques used to prepare a multifunctional biocomposite based on a hydroxyapatite (HA) coating and silver nanoparticles (AgNPs). AgNPs synthesized by a wet chemical reduction method were deposited on Ti substrates using a dripping/drying method followed by deposition of calcium phosphate (CaP) coating via radio-frequency (RF) magnetron sputter-deposition. The negatively charged silver nanoparticles (zeta potential −21 mV) have a spherical shape with a metallic core diameter of 50 ± 20 nm. The HA coating was deposited as a dense nanocrystalline film over a surface of AgNPs. The RF-magnetron sputter deposition of HA films on the AgNPs layer did not affect the initial content of AgNPs on the substrate surface as well as NPs size and shape. SEM cross-sectional images taken using the backscattering mode revealed a homogeneous layer of AgNPs under the CaP layer. The diffraction patterns from the coatings revealed reflexes of crystalline HA and silver. The concentration of Ag ions released from the biocomposites after 7 days of immersion in phosphate and acetate buffers was estimated. The obtained results revealed that the amount of silver in the solutions was 0.27 ± 0.02 μg mL −1 and 0.54 ± 0.02 μg mL −1 for the phosphate and acetate buffers, respectively, which corresponded well with the minimum inhibitory concentration range known for silver ions in literature. Thus, this work establishes a new route to prepare a biocompatible layer using embedded AgNPs to achieve a local antibacterial effect. [ABSTRACT FROM AUTHOR]

The structure and morphology of monodisperse spherical particles of (YEu)O solid solutions prepared through the low-temperature thermolysis of an amorphous precursor under isothermal conditions ( t = 800°C) have been analyzed in detail in relation to the particle size and composition. The results demonstrate that, in addition to having a polycrystalline (block) structure, the spherical (YEu)O particles are porous, with a mesoscopic residual pore size. Reducing the diameter of the spherical particles from 400 to 70 nm reduces their porosity and improves their structural perfection. The addition of Eu cations stimulates the growth of crystalline blocks that form a spherical particle, activating diffusion processes in the cation sublattice of the solid solution. [ABSTRACT FROM AUTHOR]

Results are presented of studies of the physical-mechanical properties of silver-doped calcium phosphate coatings formed by radio-frequency magnetron sputtering on a surface of technically pure VT1-0 titanium and 12Cr18Ni10Ti stainless chromium-nickel surgical steel. The films have the nanocrystalline structure of hydroxyapatite with mean diameter of the coherently diffracting domains equal to 20-30 nm. It has been established that the configuration of the magnetic field of the magnetron has an effect on the roughness, thickness, and refractive index of the coatings. The thickness of the coatings and the refractive index vary within the ranges 300-700 nm and 1.68-1.80, respectively. The nanohardness of the coatings is within the range 4-7GPa, the modulus of elasticity of the coatings depends on the material of the substrate and is equal to 130-150 GPa for titanium and 170-200 GPa for steel. Sclerometric measurements of the coatings made it possible to establish a high adhesion strength of the coatings. [ABSTRACT FROM AUTHOR]

Regularities of the formation of calcium phosphate coatings on the surface of titanium and zirconium alloys formed by the method of microarc oxidation are investigated. The scheme of deposition of the calcium phosphate coating in microarc discharges is suggested that explains the difference in the morphology, microstructure, and properties of coatings on the surface of titanium and zirconium alloys. It is demonstrated that coatings on the surface of titanium and zirconium alloys have different structures, phase compositions, and physicomechanical properties due to different electrophysical characteristics of metal (titanium and zirconium) substrates, disperse β-Nb particles, and passivating oxide films on their surfaces. [ABSTRACT FROM AUTHOR]

Theformation of silver nanoparticles during the reduction withglucose in the presence of poly(N-vinyl pyrrolidone) as capping agentwas followed for more than 3000 min. First, spherical silver nanoparticlesare formed, but in later stages, an increasing fraction of nanotrianglesand also a few nanorods develop. Both spherical and trigonal nanoparticlesgrow with time, indicating separate nucleation pathways. The domainsize in the spherical nanoparticles increases proportionally to theparticle diameter and is always about 1/4ofthe diameter, indicating that twinned seeds are formed very earlyin the process and then simply grow by extending their domains. Thelattice constant of the nanoparticles is systematically increasedin comparison to microcrystalline silver (4.0877 vs 4.08635 Å)but did not change as a function of particle diameter. A thoroughanalysis of the texture coefficient, supported by transmission electronmicroscopy data, showed that the apparently spherical particles arein fact flattened pentagonal prisms, which typically lie on theirflat pentagonal face. Neither the presence of oxygen nor the presenceof ambient light had any influence on the particle properties. [ABSTRACT FROM AUTHOR]

A comparative investigation of microstructure, mechanical and biological properties for zirconium alloyed with niobium in coarse-grained and ultra-fine grained states is presented. The temperature and deformation regimes of multi-stage abc-pressing resulted in ultra-fine grained states with an average size of the structural elements in the range of 0.28-0.55 μm, depending on the accumulated strain during pressing. The increase of the accumulated strain at each stage of pressing increased the uniformity of the structure. The microhardness increased by 50% with increased accumulated strain during the severe plastic deformation. Between the microhardness and the average size of the structural elements, a linear dependence was found, indicating a Hall-Petch relationship. The alloy had a good biocompatibility as shown by an MTT test with osteoblasts (MG-63 cell line). The good mechanical properties (microhardness) of zirconium alloyed with niobium in the ultra-fine grained state make it suitable for medical applications, e. g. as implant material. [ABSTRACT FROM AUTHOR]

A coating on the basis of silver-containing hydroxyapatite (silver-hydroxyapatite) was deposited by radio frequency (RF) magnetron sputtering. X-ray diffractometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and ellipsometry were used to analyse the change in structure and stoichiometry of the coatings upon the change of the negative electrical bias (-50 V and -100 V) on the substrate. The chemical composition of the sputter-deposited coating was identical to the target. However, an increase in the negative electrical bias on the substrate led to a decrease of the coating thickness. In addition, the average size of the grains decreased from 55 ± 15 nm (grounded substrate) up to 30 ± 10 nm when an electrical bias of -100 V was applied. [ABSTRACT FROM AUTHOR]

Abstract: Isothermal sections of the Co–Al–Nb system at 800, 1000, 1150, 1200, and 1250 °C were experimentally determined by combining results of light-optical as well as scanning electron microscopy, electron-probe microanalysis, and X-ray diffraction measurements with Rietveld analysis of heat-treated alloys and adding some results obtained from solid/liquid diffusion couples. Three polytypes of Laves phases, which are the cubic C15 and the hexagonal C14 and C36 variants, occur as stable phases in the central part of the system. The phase equilibria involving these phases were in the focus of the present study. The composition-dependence of the crystallographic properties of the Laves phases as well as the crystal structure parameters of all other occurring intermetallic phases was investigated. As in case of the binary Co–Nb system, the hexagonal Laves phases C14 and C36 are only stable at off-stoichiometric Nb contents. The preferential site occupations of the Co-, Al-, and Nb-atoms in the hexagonal lattices of the C14 and C36 Laves phase polytypes were determined by Rietveld analyses. For all binary phases except the Nb-rich phase Nb3Al, the solubility for the third element was investigated and the extensions of all phase fields were established. Besides the three Laves phases, the most striking features of the Co–Al–Nb phase diagram are the occurrence of the slowly forming L21-type Heusler phase Co2AlNb and the extended phase field of the μ phase. The existence of a μ′ phase, which was reported in the literature, is not confirmed. [Copyright &y& Elsevier]

Abstract: Thin calcium phosphate coatings with a thickness of 0.09 to 2.7 µm were prepared by radio-frequency magnetron sputtering deposition on NiTi and Ti substrates at a substrate temperature of 500 °C in argon atmosphere. Scanning electron microscopy (SEM) showed that the surface structure is uniform and dense without visible defects (pores and microcracks). Rutherford backscattering spectroscopy (RBS) and energy-dispersive X-ray spectroscopy (EDX) confirmed that the coating contains calcium, phosphorus, and oxygen with a uniform composition. Crystallographically, the coating consists of crystalline hydroxyapatite which is also supported by infrared spectroscopy. The mechanical characteristics of the coating were measured by nanoindentation (Vickers indenter), giving a nanohardness of 10 GPa and a Young''s modulus of 110 GPa. The strength of adhesion of the calcium phosphate coating to the metallic substrates depended on the coating''s thickness and decreased for a thickness larger than 1.6 µm. No difference was observed between NiTi and Ti substrates. [Copyright &y& Elsevier]

Nickel–titanium shape memory alloys (NiTi-SMA) have outstanding mechanical properties (superelasticity, shape memory effect) that make them very interesting for clinical applications. Due to the high nickel content of the material, there are concerns about possible immunological reactions of the surrounding tissue. The proliferation of osteoblast-like cells (MG-63) and the cytokine release (interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-α) from polymorphonuclear neutrophil (PMN) leukocytes as well as peripheral blood mononuclear cells (PBMC) in response to different NiTi specimen was studied:In the first two cases, the aim was to improve the biocompatibility while retaining the mechanical properties. In the third case, the effect of mechanical treatment (damage of the passivating TiO2 surface layer) was investigated. In comparison to non-coated samples the OCP/HAP-coated SMA led to an increase in the release of cytokines, in contrast, the HAP-coated samples led to a decrease in cytokine release from PBMC. The attachment, viability, and the proliferation of MG-63-cells in the near vicinity of microdrilled structures was not different from non-strained surface areas. These results show that cell-biological in vitro techniques are suitable for the prediction of tissue reactions towards implant coatings or mechanically altered NiTi-surfaces. The surface morphology (platelets versus globular particles) appear to play a significant role that supersedes that of the chemical composition of the surface. [Copyright &y& Elsevier]

A correction to the article "Wettability of Thin Silicate-Containing Hydroxyapatite Films Formed by RF-Magnetron Sputtering," by S. N. Gorodzha and colleagues that was published in the 2014 issue is presented.